Researchers of the University of Oviedo have developed a new method able to predict changes in populations of small species like sardines, anchovies and herrings from one fishing season to another. This research has just been published in the journal Ecological Applications, of the Ecological Society of America, and it focused on the collapse of anchovy (Engraulis encrasicolus) in 2005 in the Bay of Biscay, which implied closure until 2010.

The study, which is part of the PhD thesis written by Fernando G. Taboada, with the collaboration of Professor of Ecology Ricardo Anadón, was conducted due to the need to find the answer to a question: Can we determine the mechanisms for the collapse of the anchovy populations? Scientists analyzed the relevance of 3 main factors:

• Abiotic environment: changes in temperature, coastal and oceanic outcrops, dispersion barriers, river discharges, turbulences.
• Biotic environment: predator species like hake, mackerel, Spanish mackerel and competitors like sardine or horse-mackerel.
• Fishery exploitation.

The study concludes that the interaction between fishing exploitation and environmental conditions led to the collapse of this species in the Bay of Biscay in 2005

Ricardo Anadón explains that to design a new predictive model experts relied on detailed population data and a careful characterization of environmental changes experienced by anchovy populations based on satellite remote sensing in the last 20 years.

The results of this work, framed in the activities developed by the Marine Observatory of de Asturias, came to a main conclusion: "Environmental fluctuations, when isolated, do not explain the collapse of anchovy populations–explains Ricardo Anadón--. Only the impact of fishing generates a higher possibility of collapse ". An extensive analysis carried out by researchers showed the effectiveness of predictive models when analyzing the evolution of these species. "Ultimately, we have found , a new method to study the dynamics of these species exploited by fishing activities". This new mechanism will be useful to design fishing campaigns every season.

This Full professor of Ecology reminds that small pelagic fish like sardine, anchovy or herring represent one of the most exploited natural resources of all oceans. In the northern coastal area of Spain, both anchovies and sardines have been the target of fishing activity since the old times, and have always been a major economic resource, not only because of their price but also for their possibilities to be tinned industry. These species present dynamic complex populations which have meant a challenge for biologists and for the efficient management of fisheries.

Reference:

• Determining the causes behind the collapse of a small pelagic fishery using Bayesian population modeling. Ecological Applications, 26(3), 2016, pp. 886–898
• Fernando G. Taboada y Ricardo Anadón.